1. Field of the Invention
This invention is directed to indene derivatives, methods of using the derivatives and pharmaceutical compositions containing same.
2. Description of the Related Art
The normal inflammatory response is an essential localized host response to invading microorganisms or tissue injury which involves cells of the immune system. The inflammatory response allows the body to specifically recognize and eliminate an invading organism and/or repair tissue injury. The classic signs of inflammation include redness (erythema), swelling (edema), pain and increased heat production (pyrema) at the site of injury. Many of the acute changes at the site of inflammation are either directly or indirectly attributable to the massive influx of leukocytes (e.g., neutrophils, eosinophils, lymphocytes, monocytes) which is intrinsic to this response. Leukocytic infiltration and accumulation in tissue results in their activation and subsequent release of inflammatory mediators such as LTB4, prostaglandins, TNF-α, IL-1β, IL-8, IL-5, IL-6, histamine, proteases and reactive oxygen species for example.
Normal inflammation is a highly regulated process that is tightly controlled at several levels for each of the cell types involved in the response. For example, expression of the pro-inflammatory cytokine TNF-α is controlled at the level of gene expression, translation, post-translational modification, and release of the mature form from the cell membrane. Pro-inflammatory responses are normally countered by endogenous anti-inflammatory mechanisms such as generation of IL-10 or IL-4. A characteristic of a normal inflammatory response is that it is temporary in nature and is followed by a resolution phase which brings the state of the tissue back to its prior condition. The resolution phase is thought to involve up-regulation of anti-inflammatory mechanisms, such as IL-10, as well as down-regulation of the pro-inflammatory processes.
Inflammatory disease occurs when an inflammatory response is initiated that is inappropriate and/or does not resolve in the normal manner, but rather persists and results in a chronic inflammatory state. Disease may also involve a perturbation of the cellular immune response that results in recognition of host proteins (antigens) as foreign. Here, the inflammatory response becomes misdirected at host tissues with effector cells targeting specific organs or tissues often resulting in irreversible damage. The self-recognition aspect of auto-immune disease is often reflected by the clonal expansion of T-cell subsets characterized by a particular T-cell receptor (TCR) subtype in the disease state. Often inflammatory disease is also characterized by an imbalance in the levels of T-helper (Th) subsets (i.e., Th1 cells vs. Th2 cells). Inflammatory disease may be systemic (e.g. lupus) or localized to particular tissues or organs (e.g. asthma), and exerts an enormous personal and economic burden on society. Examples of some of the most common and problematic inflammatory diseases are asthma, multiple sclerosis, rheumatoid arthritis, inflammatory bowel disease, psoriasis, and atopic dermatitis.
Therapeutic strategies aimed at curing inflammatory diseases usually fall into one of two categories: (a) down-modulation of processes that are up-regulated in the disease state or (b) up-regulation of anti-inflammatory pathways in the affected cells or tissues. Most regimes currently employed in the clinic fall into the first category. Some examples of which are corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs).
Many of the tissue, cellular and biochemical processes which are perturbed in inflammatory disease have been elucidated and this has allowed the development of experimental models or assays to mimic the disease state. These assays and models enable screening and selection of compounds with a reasonable probability of therapeutic efficacy in the relevant inflammatory disease. Despite the use of these models, effective drugs have not been discovered for many inflammatory diseases. There is a significant need for therapeutic agents that effectively arrest or reverse disease progression for disease states or pathologies such as asthma, chronic obstructive pulmonary disease, multiple sclerosis, psoriasis, and inflammatory bowel disease.